The present invention relates to a body of a railway car traveling on rails, preferably a railway car body composed of hollow shape members made of light alloy.
Upon designing a railway car, one must consider how to absorb and ease the impact force loaded to the passengers on board when collision occurs. Japanese Patent Laid-Open Provisional Publication No. H7-186951 (U.S. Pat. No. 5,715,757) discloses absorbing the energy caused by the impact of the collision loaded to the front end of the leading car by the deformation thereof.
The railway car is composed of plural members being welded together. The shock absorber portion is also formed by welding plural members.
A welding method called friction stir welding is proposed as a means to weld members, which can be applied to forming railway cars. This method is disclosed in Japanese Patent No. 3014654 (EP 0797043 A2).
Japanese Patent Laid-Open Provisional Publication No. H11-51103 reports that by friction stir welding members, the metal constitution of the friction-stir-welded portion becomes refined, and the energy absorption rate is thereby improved.
According to the disclosure, friction stir welding is performed to extruded hollow shape members made of aluminum alloy in either a ring-like or spiral-like manner, the welded member being used as the steering shaft of an automobile. Friction stir welding is performed in the direction perpendicular to the direction of the impact energy, and thus the friction-stir-welded portion absorbs the impact force. Moreover, plural short pipe-shaped members are arranged linearly along the direction of impact energy, and the members are friction-stir-welded together so as to form a shaft.
Since the shock absorber portion for absorbing impact energy is mounted on the railway car body, the length of the shock absorber portion should preferably be as short as possible so as to secure enough space for the passengers. Therefore, it is desirable that a member originally included in the car body is formed as the shock absorber portion for absorbing impact energy.
The portion for absorbing impact energy is formed by joining plural members together. Therefore, the joints between the members also receive impact energy. A large amount of impact energy can be absorbed by having the shock absorber member deform into concertinas (accordion-like form). However, the welded portion is weak against impact energy, and tends to break by the impact. If the welded portion breaks, the member will no longer deform into concertinas, unable to absorb impact energy.
Thus, the present invention aims at providing a railway car body capable of absorbing impact energy.
The above object can be achieved by a railway car comprising impact energy absorption members disposed at the longitudinal ends of a car body; wherein
the impact energy absorption members absorb impact energy by deforming into concertinas by the impact energy;
the impact energy absorption members are formed by welding plural members together;
the plural members are disposed along the longitudinal direction of said car body; and
the plural members are welded together by friction stir welding.